For many years, air and gas guns were single shot models where one pellet at a time is loaded, the gun cocked and then fired. This process is repeated every time the gun is shot. One problem with a gun of this type is the difficulty in firing subsequent shots rapidly.
In attempting to overcome this problem various devices have been tried. A partial solution to this problem was the development of a spring loaded magazine. Crossman's Model 118 which uses such a magazine is bolt and cam operated. In other words, when the bolt is operated a swinging cam maneuvers a pellet into shooting position. Nevertheless, it is necessary to operate the bolt in order to fire a following shot. Another attempt at increasing a pellet gun's rate of fire can be found on the El Gamo Gamatic Repeater. However the gun must still be cocked to enable a carrier block to transfer the pellet to the air channel.
A pressurized gas or air operated repeater rifle is described in U.S. Pat. No. 4,116,193. This rifle's mechanism allows the loading of one pellet from the magazine, although a reciprocating motion of an operation lever is necessary to facilitate the movement of a carrier, and each shot requires the trigger to be pulled.
A rapid fire, fluid actuated BB gun is disclosed in U.S. Pat. No. 4,083,349 to Clifford. This gun is capable of automatic firing, but can only use round BB's and not soft lead pelletts shaped somewhat like an hour glass and hollow at their base. The BB's are stored in a magazine in a random fashion and are highly susceptible to jamming. When pressurized gas enters the chamber holding the BB's, as many BB's as can swirl into a stand pipe are swept from the bottom and fired. This results in jamming or erratic firing patterns.
Lately, a semi-automatic gas repeater has been manufactured, Daisy's Model 92, which operates by pulling the trigger. These do not need to be cocked, but still use a carrier block to transfer the pellet from the magazine to the air channel. Each shot though, still requires the trigger to be pulled.